This invention relates, in general, to injection molding and,in particular, to a new and useful method and apparatus for measuring and controlling the closing force of a plastic injection molding.
The invention relates particularly to a method of measuring and controlling the closing force of a plastics injection molding machine having a centrally adjustable knuckle joint system serving for the generation of the closing force, and to a device for the execution of this method.
In one such method, known e.g. from the German disclosure 2,910,931, the actual closing force is measured for each operating cycle and compared with two preselected tolerance limits of the set-point value; if the actual value exceeds one or the other one of these tolerance limits, the mold height is changed by an appropriately controlled servomotor, i.e. the closing force for the next cycle. The change is made in predetermined, timed steps. This closing force control mode may not only lead to a multiplicity of control steps and it does not take into account whether only an exceptional deviation is involved or whether the closing forces of successive operating cycles exceed the tolerance zone indicate an actual trend.